So he's selling a vent? DAMN! I thought he was selling the entire setup!
Then again, I don't see that vent anywhere on that prop prime. The guy's english isn't the best and this makes me think he just took some random vent/grill, painted it blue, and is now trying to sell it off as a genuine prop. I'd only buy props from the Studio's own auctions.
Even if it comes with a "Certificate of Authenticity", I'm getting this gut feeling that it's not legit.

I've seen those images before(the giant prop prime head -not the vent) on Flikr from some guys album that is entirely comprised of every movie-related picture we've seen thus far.

Anybody here ever heard of the band Ministry? Waaaay back in the 80s, they had this big metal fence they'd set up at their concerts in front of the stage for people to mosh into. Eventually, it was destroyed, but their old drummer will still occasionally buy pieces of fencing at Home Depot and put 'em on eBay as authentic Ministry mosh fences. See where I'm going with this?

Anybody here ever heard of the band Ministry? Waaaay back in the 80s, they had this big metal fence they'd set up at their concerts in front of the stage for people to mosh into. Eventually, it was destroyed, but their old drummer will still occasionally buy pieces of fencing at Home Depot and put 'em on eBay as authentic Ministry mosh fences. See where I'm going with this?

"Who exactly produced the Certificate of Authenticity for this item, and how would it allow someone to prove it's the real deal?"

The reply:

"it includes the carpenters pay stub from paramount pictures.as well as a coa"

Didn't even answer the damn question, really.

I sent him another question...let's see if he responds:

"Yes, it includes a COA, but who made the COA? How can it be trusted to show this thing is authentic?
In other words, how does the COA prove that someone didn't just go to home depot, buy a grate, and paint it?"

His reply:

"like i said it also comes with a pay stub of the carpenter that worked on the film with dates times and location call times ect..."

He once again completely dodges the question. A pay stub doesn't prove SHIT, sir.

"Who exactly produced the Certificate of Authenticity for this item, and how would it allow someone to prove it's the real deal?"

The reply:

"it includes the carpenters pay stub from paramount pictures.as well as a coa"

Didn't even answer the damn question, really.

I sent him another question...let's see if he responds:

"Yes, it includes a COA, but who made the COA? How can it be trusted to show this thing is authentic?
In other words, how does the COA prove that someone didn't just go to home depot, buy a grate, and paint it?"

His reply:

"like i said it also comes with a pay stub of the carpenter that worked on the film with dates times and location call times ect..."

He once again completely dodges the question. A pay stub doesn't prove SHIT, sir.